My Knautia Macedonica has developed powdery mildew - should I dig up and remove or is there an alternative solution?
They were planted in the position they are in now last year, but did not have this problem. They are getting plenty of sun.
Thanks in advance.

1 Jul, 2011

Answers

Leave them !
Mine get it, as do a lot of other perennials and all the mildew means is that the roots are too dry - if you cut it back and water copiously each week it'll be just fine.
Loads of the perennials in my front garden get it and that's the treatment i give them - there's definately no need to remove it.
The commonest causes are too dry soil and overcrowded planting - which doesn't allow enough air to circulate around them all.